Determinants of myocardial performance after blunt chest trauma

OBJECTIVE: This study investigates whether factors that determine myocardial performance (preload, afterload, heart rate, and contractility) are altered after isolated unilateral pulmonary contusion. METHODS: Catheters were placed in the carotid arteries, left ventricles, and pulmonary arteries of anesthetized, ventilated (FiO2=0.5) pigs (31.2+/-0.6 kg; n=26). A unilateral, blunt injury to the right chest was delivered with a captive bolt gun (n=17) followed by tube thoracostomy. To control for anesthesia and instrumentation at FiO2 of 0.5, one group received tube thoracostomy only (sham injury; n=6). To control for effects of hypoxia without chest injury, an additional sham-injury group (n=3) was ventilated with FiO2 of 0.12. To generate cardiac function (i.e., Starling) curves, lactated Ringer's solution was administered in three bolus infusions at serial time points; the slope of stroke index versus ventricular filling pressure defines cardiac contractility. RESULTS: By 4 hours after pulmonary contusion, pulmonary vascular resistance, airway resistance, and dead space ventilation were increased, whereas PaO2 (72+/-6 mm Hg at FiO2=0.5) and dynamic compliance were decreased (all p < 0.05). Despite profound lung injury, arterial blood pressure, heart rate, cardiac filling pressures, and output remained within the normal range, which is inconsistent with direct myocardial contusion. The slope of pulmonary capillary wedge pressure versus left ventricular end-diastolic pressure (LVEDP) regression was reduced by more than 50% from baseline (p < 0.05), but there was no significant change in the slope of the central venous pressure versus LVEDP regression. By 4 hours after contusion, the slope of the stroke index versus LVEDP curve was reduced by more than 80% from baseline (p < 0.05). By the same time after sham injury with FiO2 of 0.12 (PaO2 < 50 mm Hg), the regression had decayed a similar amount, but there was no change in the slope after sham injury with FiO2 of 0.5 (PaO2 > 200 mm Hg). CONCLUSION: After right-side pulmonary contusion, the most often used estimate of cardiac preload (pulmonary capillary wedge pressure) does not accurately estimate LVEDP, probably because of changes in the pulmonary circulation or mechanics. Central venous pressure is a better estimate of filling pressure, at least in these conditions, probably because it is not directly influenced by the pulmonary dysfunction. Also, ventricular performance can be impaired by depressed myocardial contractility and increased right ventricular afterload even with normal left ventricular afterload and preload. It is thus conceivable that occult myocardial dysfunction after pulmonary contusion could have a role in the progression to cardiorespiratory failure even without direct cardiac contusion.     

Acute and chronic effects of bilateral lung transplantation without cardiopulmonary bypass on the first transplanted lung

BACKGROUND: Bilateral lung transplantation (BLT) without cardiopulmonary bypass (CPB) may exacerbate reperfusion injury to the initially engrafted lung because of increases in pulmonary flow during implantation of the second graft. METHODS: In a retrospective review of 23 BLT patients, we hypothesized that BLT without CPB injures the first transplanted lung measured by acute and late graft dysfunction compared to the second transplanted lung. Of the 23 BLT, 19 underwent transplantation without CPB while 4 patients were placed on CPB secondary to hemodynamic instability. RESULTS: Acute graft function was assessed by radiographic scoring of lung quadrants (blinded radiologist; 0 = no infiltrate; 1 = infiltrate; maximum = 2 per lung) and by arterial/alveolar oxygen tension ratios (PaO2/ FiO2) ratios. Late graft function was evaluated by quantitative perfusion scan. Lung perfusion was graded as abnormal if less than 50% on the right or less than 45% on the left (Fisher's exact). Radiographic scores were not different between first and second implanted lungs at 1 and 24 hours, PaO2/FiO2 ratios at 1 and 24 hours were 273+/-26 and 312+/-23, respectively, and perfusion scans at 3 and 12 months revealed normal differential blood flow. CONCLUSIONS: These findings suggest no acute or chronic differences occur between the first or second transplanted lung completed without CPB.     

Inhaled nitric oxide in patients with cystic fibrosis during preoperative evaluation and during anaesthesia for lung transplantation

INTRODUCTION: Inhaled nitric oxide (iNO) has been recently used as pulmonary vasodilator without any systemic effects because of a rapid inactivation by haemoglobin. We studied haemodynamic and oxygenation effects during iNO administration in cystic fibrotic patients during preoperative evaluation and during anaesthesia for lung transplantation. METHODS: From March 1996 to November 1997, 35 patients received iNO (40 ppm) during preoperative evaluation in spontaneously breathing. 13 patients, who underwent double lung transplantation, received iNO (40 ppm) during the surgical procedures, after pulmonary artery clamping. RESULTS: In the preoperative evaluation a significant decrease of mean pulmonary artery pressure, pulmonary vascular resistance index and intrapulmonary shunt, with an increase of PaO2/FiO2, were observed during iNO administration, compared to baseline in 100% O2. During lung transplantation a significant decrease in intrapulmonary shunt was noted. All the transplants were successfully performed without cardio-pulmonary bypass. In all procedures, after iNO administration, we observed no modification of systemic haemodynamics. In conclusion, our study confirms the pulmonary effects of iNO without any systemic effects in patients affected by cystic fibrosis during preoperative evaluation and during anaesthesia for lung transplantation.     

支气管阻塞器用于胸腔镜下肺癌术患者单肺通气的效果

Objective: The aim of this study was to observe the effect of endobronchial blocker tube in the pulmonary carcinoma with video-assisted thoracic surgery. Methods: Forty patients of pulmonary carcinoma with video-assisted thoracic surgery were randomly assigned into two groups with twenty cases each : endobronchial blocker tube group (group 1) and double-lumen endobronchial tube group (group 2). After anesthesia was induced, in group 1, single lumen tube was intubated at first, and then endobronchial blocker tube intubated to left or right primary bronchus under the guidance of fiber-optic bronchoscope according to operational necessary, injected 2–4 mL air to blocker balloon and blocker one lateral primary bronchus for one-lung ventilation necessarily; while in group 2, the position of double-lumen endobronchial tube was confirmed with fiber-optic bronchoscope after intubation. Blood samples were collected before anesthesia induction, double lumen ventilation, at the one-lung ventilation of 5 min, 30 min, 60 min, 120 min and 180 min, SBP, DBP, HR, SpO2, partial pressure of end tidal carbon dioxide (PetCO2), pH, PaO2, PaCO2,PaO2/FiO2 were recorded. Results: Forty cases' intubations were all successful. There were no differences in SBP, DBP, HR, SpO2, PetCO2, pH, PaCO2 between two groups in different points (P > 0.05). Paw in group 1 was lower than group 2, PaO2 and PaO2/FiO2 in group 1 was higher than group 2 in the one lung ventilation of 5 min, 30 min, 60 min, 120 min and 180 min. Conclusion: The endobronchial blocker tube can meet the request of video-assisted thoracic surgery, with the special advantages of simple insertion, lower airway and better oxygenation. Endobronchial blocker tube offer a new way for one-lung ventilation in the pulmonary carcinoma with video-assisted thoracic surgery.     

Destructive gouty arthritis of the hip

We present a case of a 19-year old female with systemic pulmonary artery (PA) pressure due to a congenital ventricular septal defect (VSD) and atrial septal defect (ASD). She was pink at rest and cyanotic on exercise. Lung biopsy revealed grade IV pulmonary vascular changes. As a preliminary step PA was banded to increase right-to-left shunt and decrease aortic (Ao) saturation with consequent decrease in PA saturation. After one year, when she was no longer cyanotic, even on exercise, lung biopsy revealed total regression of pulmonary vascular changes. As a definitive procedure VSD and ASD were closed and PA was debanded. Cardiac catheterization one week postoperatively showed PA pressure to be 50% of systemic pressure. We postulate that reversal of pulmonary vascular changes were due to lowered PA saturation. We further believe that lower PA pressure could have contributed to this regression of pulmonary vascular changes. We performed the same procedure in six more patients with similar positive clinical response. This new concept brings renewed hope to many children who otherwise are candidates for heart lung transplantation.     

Detection and clinical pathological significance of the expression of P21, P185, p53 proteins and mutation of ras, p53 genes in transitional cell carcinoma of the bladder

OBJECTIVE: In order to observe the effects of inhaling nitric oxide (NO) on acute lung injury (ALI). METHODS: 24 rabbits divided into 4 groups. Six rabbits injured with intravenous E. Coli endotoxin, then followed by treatment of inhaling 80 ppm NO in inspired gas. Before and after the infusion of endotoxin, the mean pulmonary arterial pressure (mPAP), mean systemic arterial pressure (mPSA) and the PaO2 were examined. The venous methemoglobin (MHb) was measured by using spectrophometer colorimitry. The extravasculur lung water was evaluated with rate of dried to wet lung weight at the end of study. RESULTS: The rabbits injured with endotoxin inhaling 80 ppm NO could rapidly reduce the mPAP, increase the PaO2 and without inducing significant change of mPSA, MHb and extravasculur lung water. CONCLUSIONS: Inhalation of 80 ppm NO can selectively cause pulmonary artery dilatation, reduce mPAP, improve pulmonary gas exchange, without producing system vasodilation and toxic effects to the rabbits.     

Antihypertensive treatment and serum cholesterol: results of population-based surveys in the German Cardiovascular Prevention Study

OBJECTIVES: This study was done to clarify which diameter, that of the pulmonary arteries (PAs) or that of the pulmonary veins (PVs), more precisely reflects pulmonary blood flow (PBF) bilaterally and unilaterally. METHODS: To evaluate bilateral PBF, we studied 15 consecutive patients with Kawasaki disease as normal patients and 30 patients with tetralogy of Fallot who received cardiac catheterization. To evaluate unilateral PBF, 20 patients with various congenital heart diseases undergoing cineangiography and lung perfusion scintigraphy were studied. The diameter of PA was measured immediately proximal to the origin of the first lobar branches bilaterally, and right PA area, left PA area, PA area (mm2), and PA index (mm2/m2) were calculated. The diameter of PV was also measured distal to the junction with the left atrium. Right PV area, left PV area, PV area (mm2), and PV index (mm2/m2) were calculated from these diameters. Pulmonary blood flow (PBF) was obtained by the Fick method during catheterization. To evaluate unilateral PBF, PBF was divided into right and left PBF according to the right/left perfusion ratio measured by lung perfusion scintigraphy. RESULTS: Evaluation of bilateral PBF was as follows: in normal patients, PA and PV areas were correlated with body surface area (r = 0.88, p = 0.0001 and r = 0.93, p = 0.0001); PA index and PV index ranged from 248 to 436 (mean = 343) mm2/m2 and from 346 to 595 (mean = 466) mm2/m2, respectively, and were constant irrespective of body surface area; PA and PV areas were correlated with PBF in normal patients, as well as in patients with tetralogy of Fallot. There was a better correlation between PV area and PBF than between PA area and PBF in normal patients, as well as a significantly better correlation in patients with tetralogy of Fallot. Evaluation of unilateral PBF was as follows: right PV area was correlated with right PBF (p = 0.0002), while right PA area was not; left PV area and left PA area were correlated with left PBF; right/left PV area ratio was correlated with the right/left perfusion ratio with better agreement than right/left PA area ratio. CONCLUSION: Our data suggest that the size of PVs in patients with congenital heart disease may be more useful than the size of PAs to indicate bilateral and unilateral PBF than the size of PAs. Differences in PV area of each lung may be a suitable indicator of discrepancy in blood flow to each lung.     

Dental practices continue to enlarge: even in the state of Illinois

OBJECTIVES: To determine the effect of propofol on pulmonary short circuit or shunt (Qs/Qt). PATIENTS AND METHODS: Nine patients undergoing scheduled thoracic surgery with single lung ventilation were studied. All patients were anesthesized with 2 mg/kg propofol followed by a continuous infusion of 4-6 mg/kg/h; fentanyl 0.3 mg followed by bolus as needed; and relaxed with atracurium 0.5 mg/kg followed by bolus of 0.1-0.2 mg/kg as needed. The ratio Qs/Qt was calculated with an FiO2 of 1 and patients in lateral decubitus. RESULTS: During double-lung ventilation Qs/Qt was 17.4 +/- 5.4% and PO2 was 430 +/- 16 mmHg, while shunt increased to 27.8 +/- 8.4% and PO2 decreased to 258 +/- 127 mmHg during single-lung ventilation. Change was significant in both cases. CONCLUSIONS: Continuous infusion of propofol produces a significant increase of Qs/Qt and a significant decrease of PaO2 during single-lung ventilation for thoracic surgery.     

Polygraphic validation of distraction tasks in clinical differential tremor diagnosis

We studied the effect of inhaled nitric oxide (NO) on 80 patients who had undergone cardiac surgery in our center. The indications for receiving NO inhalation and the number of patients were as follows: Pp/Ps > 0.5 for pulmonary hypertension (PH) (n = 32; 21 children and 11 adults), severe PH crisis (n = 9), high pulmonary vascular tone (Glenn pressure more than 18 mm Hg after bidirectional Glenn operation) or arterial oxygen saturation (SaO2) less than 70% despite an FiO2 of 1.0 after Blalock-Taussig shunt (n = 6), mean pulmonary artery pressure (PAP) > 15 mm Hg and transpulmonary gradient (TPG) (mean PAP - left atrial pressure [LAP]) > 8 mm Hg after Fontan-type operation (n = 18), elevated pulmonary vascular tone (mean PAP > 30 mm Hg and left ventricular assist system [LVAS] flow rate < 2.5 L/min/m2) in patients with LVAS (n = 3), and impaired oxygenation (PaO2/FiO2 < 100 under positive end-expiratory pressure [PEEP] > 5 cm H2O) (n = 12). Low dose inhaled NO (10 ppm) had the following effects. In adult PH patients, it significantly reduced the mean PAP (from 37.3 to 27.0 mm Hg; average values are given) and increased the mean systemic arterial pressure (SAP) (64.7 to 75.3 mm Hg). In infant PH patients, it increased the mean SAP (51.8 to 56.1 mm Hg). In patients with a PH crisis, it significantly reduced the central venous pressure (CVP) (13.3 to 8.8 mm Hg) while increasing both the mean SAP (49.4 to 57.9 mm Hg) and PaO2/FiO2 (135 to 206). In patients after a Fontan-type operation, it significantly reduced the mean PAP (16.8 to 13.8 mm Hg) and TPG (9.5 to 5.8 mm Hg). In patients under LVAS, it reduced the CVP (11.7 to 8.0 mm Hg) and mean PAP (32.0 to 24.7 mm Hg). In impaired oxygenation patients, PaO2/FiO2 was increased (75 to 106). Sixty-five patients were all followed for 2.0-4.3 years (average, 3.1 years). All 65 patients remained free from oxygen requirement, and possible chronic adverse effects including the occurrence of malignant tumors or chronic inflammation in the respiratory tract were not observed.     

Controlled reperfusion of cardiac grafts from non-heart-beating donors

BACKGROUND: Hearts harvested from non-heart-beating donors sustain severe injury during procurement and implantation, mandating interventions to preserve their function. We tested the hypothesis that limiting oxygen delivery during initial reperfusion of such hearts would reduce free-radical injury. METHODS: Rabbits sustained hypoxic arrest after ventilatory withdrawal, followed by 20 minutes of in vivo ischemia. Hearts were excised and reperfused with blood under conditions of high arterial oxygen tension (PaO2) (approximately 400 mm Hg), low PaO2 (approximately 60 to 70 mm Hg), high pressure (80 mm Hg), and low pressure (40 mm Hg), with or without free-radical scavenger infusion. Non-heart-beating donor groups were defined by the initial reperfusion conditions: high PaO2/ high pressure (n = 8), low PaO2/high pressure (n = 7), high PaO2/low pressure (n = 8), low PaO2/low pressure (n = 7), and high PaO2/high pressure/free-radical scavenger infusion (n = 7). RESULTS: After 45 minutes of reperfusion, low PaO2/ high pressure and high PaO2/low pressure had a significantly higher left ventricular developed pressure (63.6 +/- 5.6 and 63.1 +/- 5.6 mm Hg, respectively) than high PaO2/high pressure (40.9 +/- 4.5 mm Hg; p < 0.0000001 versus both). However, high PaO2/high pressure/free-radical scavenger infusion displayed only a trend toward improved ventricular recovery compared with high PaO2/ high pressure. CONCLUSIONS: Initially reperfusing nonbeating cardiac grafts at low PaO2 or low pressure improves recovery, but may involve mechanisms other than decreased free-radical injury.     

Superior ophthalmic vein at computed tomography

Simultaneous hemodynamic, ventilatory, and blood gas studies were performed in 16 men with congestive heart failure before and during infusion of sodium nitroferricyanide (nitroprusside). The cardiac index increased from 2.00+/-0.16 L/min/sq m (SE) to 2.38+/-0.14 L/min/sq m, and the total pulmonary and systemic peripheral resistances fell from 928+/-123 to 494+/-57 dynes sec cm-5 and from 2,208+/-210 to 1,558+/-121 dynes sec cm-5, respectively. Both systemic and pulmonary arterial decreased during infusion of sodium nitroferricyanide, and the mixed venous oxygen pressure increased. There was no change in total or alveolar ventilation, arterial carbon dioxide tension, pH, or base excess; however, the mean arterial oxygen pressure (PaO2) decreased from 74+/-3 mm Hg to 68+/-3 mm Hg and the venous admixture effect increased from 8+/-1% to 13+/-2%. We conclude that the decrease in PaO2 during infusion of sodium nitroferricyanide resulted from a worsening of the ventilation-perfusion relationships due to increased perfusion of underventilated pulmonary units.     

Measurement of lung volume and DLCO in acute respiratory failure

We have undertaken rebreathing measurements of functional residual capacity (FRC), carbon monoxide diffusing capacity (DLCO), and diffusing coefficient (KCO) during positive pressure ventilation in 15 patients with adult respiratory distress syndrome (ARDS). Measurements of oxygenation (PaO2:FIO2 ratio) and lung injury score (LIS) were also recorded. Eight patients subsequently died (mortality of 53%). There was no significant difference in mean FRC, PaO2:FIO2, or LIS at presentation between survivors and nonsurvivors. However, both DLCO and KCO at presentation were significantly greater in survivors than nonsurvivors. In a separate study of nine patients with less severe lung injury, pulmonary capillary blood volume, derived from values of DLCO measured at two different values of FIO2, correlated with invasive pulmonary vascular resistance (PVR) measurements (r = 0.84, p < 0.01). DLCO measurements can be successfully undertaken in patients being ventilated with acute lung injury and may be a useful, noninvasive method of assessing the pulmonary circulation. The lowest values of DLCO were recorded in patients who subsequently did not survive.     

Influence of hypertonic saline solution infusion on defibrillation efficacy

BACKGROUND: Transplantation of lung allografts from the same donor into 2 recipients ("twinning") provides an opportunity to study recipient and donor factors that influence early allograft function. METHODS: Twenty-seven pairs of recipients were identified and evaluated using multivariate logistic regression analysis (p < 0.05). Four measures of early graft function were analyzed: alveolar-arterial gradient in the operating room, first alveolar-arterial gradient in the intensive care unit, alveolar-arterial gradient at 24 hours, and days of mechanical ventilation. RESULTS: Analysis of the pooled data without regard to pairing showed that alveolar-arterial gradient in the operating room was influenced by donor age, length of donor hospitalization, recipient mean pulmonary artery (PA) pressure at unclamping, and transplantation of a left lung. The alveolar-arterial gradient in the intensive care unit was correlated with donor age, donor cause of death, and mean PA pressure on arrival in that unit. Only mean PA pressure remained significant at 24 hours. Days of mechanical ventilation was determined by mean PA pressure on arrival in the intensive care unit, drop in mean PA pressure during operation, and diagnosis of the recipient. In the paired analysis, receiving a left lung, recipient diagnosis (pulmonary hypertension worse than others), and need of cardiopulmonary bypass were significantly associated with immediate graft dysfunction, although these influences did not persist beyond the immediate postoperative period. Donor arterial oxygen tension and time of ischemia were not significant predictors in any analysis. CONCLUSIONS: Immediate allograft function was associated with donor-related characteristics initially, but these lost importance over the ensuing 24 hours. Recipient PA pressure was an immediate and persisting influence. In the analysis of differences in function between the members of each pair, transplantation of the left lung, recipient diagnosis, and cardiopulmonary bypass were identified, but their influence did not persist beyond the first 6 hours.     

Estimation of pulmonary artery pressure by spectral analysis of the second heart sound

The objective of the present work was to test and validate a noninvasive method based on spectral analysis of the second heart sound (S2) to estimate the pulmonary artery (PA) systolic pressure in 89 patients with a bioprosthetic heart valve. The technique was compared with continuous-wave Doppler estimation of PA systolic pressure in these patients. The heart sounds recorded at the pulmonary area on the chest wall were digitized by computer. The spectra of S2 and those of the aortic (A2) and the pulmonary (P2) components of S2 were computed with a fast-Fourier transform. Seven features were extracted from these spectra. The statistical analysis performed with the Pearson linear correlation coefficient showed that the best estimation of PA systolic pressure obtained by spectral phonocardiography (r = 0.84, SEE +/- 5.6 mm Hg, p <0.0001) was provided by the following equation: PA systolic pressure = 47 + 0.68 Fp - 4.4 Qp - 17 Fp/Fa - 0.15 Fs, where Fs and Fp are dominant frequencies associated with the maximal amplitude of the power spectra of S2 and P2, respectively, Qp is the quality of resonance of P2, and Fp/Fa is the ratio of the dominant frequencies of P2 and A2, respectively.     

Thoracic surgery and liver dysfunction

Lung resection results in loss of lung parenchyma including residual healthy lung tissue and in reduction in pulmonary vascular bed. A decrease in residual pulmonary vascular bed after lung resection causes an increase in right heart afterload, and in some patients, it would be associated with an increase in right heart preload and consequent the changes in hepatic circulation which would lead to liver damage. Preceding thoracotomy, unilateral pulmonary arterial occlusion test (UPAO) was performed to simulate the hemodynamic changes after lung resection to evaluate the increase in right heart preload after surgery. Patients with the decreases in cardiac index or PaO2 during UPAO showed a higher levels of GPT during postoperative period when compared with those with the increase in either parameters. In a surgical treatment for empyema, bronchiectasis, or other infectious lung diseases, bronchial angiography (BAG) and also bronchial arterial embolization (BAE) were useful methods to prevent from exceeding bleeding during thoracotomy, which is one of the risk factors to cause liver damage after surgery. These results suggest that, in the field of thoracic surgery, the preoperative assessment of the hemodynamic changes caused by lung resection and the preoperative attempt to prevent from bleeding during thoracotomy are both important to protect from liver damage caused by surgical stress.     

The role of a 40-megadalton plasmid in the adherence and hemolytic properties of Aeromonas hydrophila

Thirty ventilation-perfusion pulmonary scintigraphic studies were performed in 13 patients who had undergone unilateral lung transplantation. Ventilation-perfusion mismatch (ventilation better than perfusion) was judged absent, mild, moderate, or severe in the transplanted and native lungs. Ventilation-perfusion mismatch was significantly worse in the transplanted lungs (p < .0001). Findings of lung biopsies and chest roentgenograms failed to correlate with the severity of ventilation-perfusion mismatch. Hypoxic pulmonary vasoconstriction appears to be significantly impaired in most unilateral lung transplants; the mechanism for this impairment is unclear.     

The operability of patient with pulmonary hypertension judged from hemodynamic changes before and after surgery

1) In congenital heart disease with pulmonary hypertension, the place for surgical correction still remains even with almost systemic PA pressure if R to L shunt ratio on lung scintigram is lower than 25%. 2) The patient with pulmonary hypertension in congenital heart disease younger than 3 years of age has wider acceptability for surgery compared to older patient. 3) In patients with mitral valvular disease, surgical correction seems to be indicated irrespective of PA pressure, if their preoperative U/L are lower than 2.4.     

Does airway pressure release ventilation alter lung function after acute lung injury?

BACKGROUND: During airway pressure release ventilation (APRV), tidal ventilation occurs between the increased lung volume established by the application of continuous positive airway pressure (CPAP) and the relaxation volume of the respiratory system. Concern has been expressed that release of CPAP may cause unstable alveoli to collapse and not reinflate when airway pressure is restored. OBJECTIVE: To compare pulmonary mechanics and oxygenation in animals with acute lung injury during CPAP with and without APRV. DESIGN: Experimental, subject-controlled, randomized crossover investigation. SETTING: Anesthesiology research laboratory, University of South Florida College of Medicine Health Sciences Center. SUBJECTS: Ten pigs of either sex. INTERVENTIONS: Acute lung injury was induced with an intravenous infusion of oleic acid (72 micrograms/kg) followed by randomly alternated 60-min trials of CPAP with and without APRV. Continuous positive airway pressure was titrated to produce an arterial oxyhemoglobin saturation of at least 95% (FIO2 = 0.21). Airway pressure release ventilation was arbitrarily cycled to atmospheric pressure 10 times per minute with a release time titrated to coincide with attainment of respiratory system relaxation volume. MEASUREMENTS: Cardiac output, arterial and mixed venous pH, blood gas tensions, hemoglobin concentration and oxyhemoglobin saturation, central venous pressure, pulmonary and systemic artery pressures, pulmonary artery occlusion pressure, airway gas flow, airway pressure, and pleural pressure were measured. Tidal volume (VT), dynamic lung compliance, intrapulmonary venous admixture, pulmonary vascular resistance, systemic vascular resistance, oxygen delivery, oxygen consumption, and oxygen extraction ratio were calculated. MAIN RESULTS: Central venous infusion of oleic acid reduced PaO2 from 94 +/- 4 mm Hg to 52 +/- 9 mm Hg (mean +/- 1 SD) (p < 0.001) and dynamic lung compliance from 40 +/- 6 mL/cm H2O to 20 +/- 6 mL/cm H2O (p = 0.002) and increased venous admixture from 13 +/- 3% to 32 +/- 7% (p < 0.001) in ten swine weighing 33.3 +/- 4.1 kg while they were spontaneously breathing room air. After induction of lung injury, the swine received CPAP (14.7 +/- 3.3 cm H2O) with or without APRV at 10 breaths per minute with a release time of 1.1 +/- 0.2 s. Although mean transpulmonary pressure was significantly greater during CPAP (11.7 +/- 3.3 cm H2O) vs APRV (9.4 +/- 3.8 cm H2O) (p < 0.001), there were no differences in hemodynamic variables. PaCO2 was decreased and pHa was increased during APRV vs CPAP (p = 0.003 and p = 0.005). PaO2 declined from 83 +/- 4 mm Hg to 79 +/- 4 mm Hg (p = 0.004) during APRV, but arterial oxyhemoglobin saturation (96.6 +/- 1.4% vs 96.9 +/- 1.3%) did not. Intrapulmonary venous admixture (9 +/- 3% vs 11 +/- 5%) and oxygen delivery (469 +/- 67 mL/min vs 479 +/- 66 mL/min) were not altered. After treatment periods and removal of CPAP for 60 min, PaO2 and intrapulmonary venous admixture returned to baseline values. DISCUSSION: Intrapulmonary venous admixture, arterial oxyhemoglobin saturation, and oxygen delivery were maintained by APRV at levels induced by CPAP despite the presence of unstable alveoli. Decrease in PaO2 was caused by increase in pHa and decrease in PaCO2, not by deterioration of pulmonary function. We conclude that periodic decrease of airway pressure created by APRV does not cause significant deterioration in oxygenation or lung mechanics.     

Timing and priorities for cystic fibrosis patients candidates to lung transplantation

Bilateral lung transplantation is actually considered a valuable option for patients with endstage lung disease related to cystic fibrosis. Timing is crucial to transplant successfully as many patients as possible and it is mainly based on the progressive worsening of pulmonary function tests and quality of life. We reviewed the charts of all patients accepted for lung transplantation at our institution, in order to assess the role of several functional and demographic parameters; we compared the group of patients able to successfully wait for transplantation (Group A) with patients dying on the waiting list (Group B). Twenty-eight patients were accepted: 15 were successfully transplanted (2 at other institutions) (mean waiting time: 117 days), 7 died waiting (mean waiting time: 108 days) and 6 are still on the list. We recorded FEV-1, FVC, PaO2, PaCO2, supplemental O2 requirement, 6-minute walking test, right ventricular ejection fraction (RVEF) and cardio-pulmonary hemodynamics measured at right heart catheterization; we recorded also age at time of diagnosis and at time of evaluation, sex, weight and Schwachman score. These parameters were compared between Group A and B. Age at time of evaluation, sex, weight and Schwachman score did not present any difference between the two groups, as well as pulmonary function tests, PaO2, 6-minute walk test and RVEF. A statistically significant difference was found in terms of PaCO2 (43.9 +/- 9.3 in Group A vs 69.1 +/- 32.4 in Group B, heart rate at rest (102 +/- 21 vs 131 +/- 12) mean pulmonary artery pressure (20.6 +/- 2.9 vs 36 +/- 15.7), pulmonary vascular resistances (350 +/- 96 vs 460 +/- 119.4), cardiac index (3.2 +/- 0.6 vs 5.4 +/- 0.9). On the base of our initial experience we conclude that a careful evaluation of CF candidates for lung transplantation is recommended. A deterioration of pulmonary function tests and quality of life are useful parameters to accept patients in the waiting list; however priority should be attributed also on the base of cardio-pulmonary hemodynamics. A larger series of patients is required to draw definitive conclusions.     

Attenuation of lung graft reperfusion injury by a nitric oxide donor

OBJECTIVE: One of the primary features of ischemia-reperfusion injury is reduced production of protective autocoids, such as nitric oxide, by dysfunctional endothelium. Administration of a nitric oxide donor during reperfusion of lung grafts may therefore be beneficial through modulation of vascular tone and leukocyte and platelet function. METHODS: Rat lung grafts were flushed with University of Wisconsin solution and reperfused for 1 hour in an ex vivo model incorporating a support animal. Group I grafts (n = 6) were reperfused immediately after explantation, group II (n = 6) and III (n = 5) grafts after 24 hours of storage at 4 degrees C. In group III, glyceryl trinitrate, a nitric oxide donor, was administered during the first 10 minutes of reperfusion at a rate of 200 micrograms/min. In an additional group (n = 5), 200 micrograms/min hydralazine was administered instead, to assess the effect of vasodilation alone. RESULTS: Graft function in group II deteriorated compared with that in group I, with significant reduction of graft effluent oxygen tension and blood flow and elevation of pulmonary artery pressure, peak airway pressure, and wet/dry weight ratio. In contrast, in group III, glyceryl trinitrate treatment improved graft function to baseline levels in all these parameters. Administration of hydralazine, meanwhile, produced mixed results with only two out of five grafts functioning at control levels. CONCLUSIONS: In this model, administration of glyceryl trinitrate to supplement the nitric oxide pathway in the early phase of reperfusion has a sustained beneficial effect on lung graft function after 24-hour hypothermic storage, probably through mechanisms beyond vasodilation alone.